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I replaced the original flash hider on MP10 with an A2 style one. Since I was unable to index it (going from about 1:00 o'clock position all the way to 12:00 o'clock) I used the old crush washer that came withe rifle for a shim to be able to time it correctly.

IF it wasn't completely crushed in its first use (i.e. it wasn't mashed flat), in which case it should be fine. Otherwise Terry is correct, 1-time use if it cannot be crushed anymore. Simple thing is to just watch it. If it doesn't loosen, you're fine, if it does, replace the $1 piece.

My problem was that I couldn't crush the washer, should I just use more force? I don't want to break anything, I was already cranking hard and still had around 3/4 of a full revolution to go. That's when I decided to use the old washer for a shim.

My problem was that I couldn't crush the washer, should I just use more force? I don't want to break anything, I was already cranking hard and still had around 3/4 of a full revolution to go. That's when I decided to use the old washer for a shim.

I don't remember ever having to bust a nut trying to get a crush washer to do its job. None the less, if it stays tight it's fine. Just check it by hand after each firing session to make sure it has stayed tight. Not hurting a thing.

A decent torque wrench doesn't lie and even a cheap torque wrench is enough to keep you reigned in with an AR barrel nut and muzzle device. Seen barrels twisted and extension index pins sheared but everyone should own at least a basic Craftsman torque wrench even if to change a flat tire on wife's car without warping brake rotors. Craftsman has a 10 to 75 ft/lb microclick wrench for $49.99 and 5 to 80 ft/lb digi-click wrench for $79.99. I keep a cheap 3/8" drive and 1/2" drive Craftsman in most trucks and then when matters use CDI, Snap-On or similar quality wrench.

Most major brand professional wrenches are all made in same plant. It's why Snap-On bought CDI, if you buy any American made hand tool whether Snap-On, MAC, Craftsman or whoever it was made by one of two companies, Armstrong or Proto. They make everyone's hand tools to specifications down to branding. Have a bunch of spline drive Stanley impact sockets and when look closely can tell they are made by Proto.

If I were building one AR and maintaining a few along with other rifles the $79 Craftsman digi-torque with 5 to 80 ft/lb range would be minimum quality and range acceptable. Most torque wrenches have more error closer get to bottom end or top end of their range. A 10 to 70 ft/lb wrench is technically in the range needed except at 10 and 70 will have error. While muzzle devices should be torque to 20 ft/lbs a 10 ft/lb wrench is right on edge of its accuracy range. With barrel nuts range of 35 to 80 ft/lbs the 10 to 70 ft/lb wrench will always be at edge of its total range and not be highly accurate if trying to nudge a nut another fuzz to get gas tube to fit.

Why I have inch/ounce in different values for 0 to 1 inch/ounce in hundredths, 0 to 10 inch/ounces in tenths, up to 10 to 25 inch/ounces. When go to inch/lbs have variety of ranges and resolution and up to 8,800 ft/lbs which some can't imagine needing but have had to use it on big monopole billboards where have a 10,000 pound sign 100 feet in the air supported by a single pole bolted to a cement footer with huge blots tied to a footing the size of a small building. Same with cell towers, do you want a cell tower falling across the road on your families?

On opposite end snapping off an M1 screw or snapping a surface mount circuit board because over tightened the board or have it shake loose due to not tightening enough. Want the radar in airplane your flying on going out because technician didn't have an inch/ounce wrench? Not all people work on the variety of items I do and don't need a dozen standard torque wrenches plus half dozen 10,000 volt insulated torque wrenches with current certificates of calibration but honestly feel that a basic inch/pound and foot/pound torque wrench is required for your "man card". Like a chain saw, decent hand tool selection, 1911, AR 15, battle rifle and pickup truck or real SUV it's just part of what you should have and takes a lot of guess work out of life.

Learned from my rifle smith after buying a $1,000 to $5,000 scope, properly installing and lapping the rings, properly torqueing the screws are as important as dropping the cash on the scope. The labor he put into mounting a scope was monumental. He would basically remachine all the mating surfaces making sure all was flat, square, etc. First rifle he built for me had $800 in scope upgrades and mounting charges. Took him a $1,000 plus scope in 1980's dollars, bases and rings he requested and said soon as scope came back from having glass trued and properly purged would have the mounts ready to drop scope in rings. Watched him spend over an hour leveling rifle, scope and then slowly torqueing screws in very specific pattern till had it ready to bore sight which he did by eye looking down bore at 100 yard target then when sent first round was within 1.5 inches at 100 yards thus very few clicks of adjustment were lost for doping scope.

I wouldn't mount a scope without using an inch/pound wrench as well as mounting barrel nuts and muzzle devices without an foot/pound wrench. Have the most meticulous barrel nut routine that many know I am insane if in shop when mount a barrel. After squaring then cleaning and degreasing all parts surgical clean according to snugness of extension in receiver may use some bedding compound. May be thin layer of blue Loctite or actual wrap of machinists shim stock which have in several widths and increments of a thousanth inch. Nut is torqued to preload value and left for half hour to an hour then removed and threads allowed to relax. Reassemble and torque to near final value that's my favorite, left again for half hor to hour and removed to be allowed to relax again. Then torque nut to value I prefer +/- a fuzz to be very close on gas tube alignment. If nUT does not line up close at my favorite torque value pull and shim till get notch aligned very close for tube, let sit another hour then torque it one more time so all is aligned, threads have been preloaded to avoid stretch and all is happy.

I preload,loosen and then final torque or torque to intermediate value and retorque following certain pattern of rotation thats either to book specifications or my own habits if book or manufacturers don't have a recommended rotation from fastener to fastener. When leave tire shop even though watched them torque lug nuts I pull center caps and check with my wrench. Back when sent majority of truck service work out had one come back from brake shop and discovered one wheel the lug nuts were only finger tight. Yes I am super anal about torque and meter readings but may be reason get 300,000 minimum out of gas burning trucks and half million out of diesels. Also once rifles go through initial adjustment first trip to range they don't break or give problems.

__________________
A time will come when people will not listen to accurate teachings. Instead, they will follow their own desires and surround themselves with teachers who tell them what they want to hear. 2 Timothy 4:3 G.W.T.
"If it is worth doing once...it's worth doing it a few more times to get it right." Stimpsonjcat

My problem was that I couldn't crush the washer, should I just use more force? I don't want to break anything, I was already cranking hard and still had around 3/4 of a full revolution to go. That's when I decided to use the old washer for a shim.

I can relate to this.
My least favorite AR job is timing A2 flash hiders with crush washers.
That is why I use three prong or A1 flash hiders...set em and forget em!
I embrace the big ole lock washer that was used in the early days of the M16.
Also other types of muzzle devices that require no timing are gtg in my book, too.

I can relate to this.
My least favorite AR job is timing A2 flash hiders with crush washers.
That is why I use three prong or A1 flash hiders...set em and forget em!
I embrace the big ole lock washer that was used in the early days of the M16.
Also other types of muzzle devices that require no timing are gtg in my book, too.

Same here. A2ís get replaced and use the lock washer.

__________________
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Ghandi

"We, here in America, hold in our hands the hopes of the world, the fate of the coming years; and shame and disgrace will be ours if in our eyes the light of high resolve is dimmed, if we trail in the dust the golden hopes of men."

The way I normally install a F/H is to take a 3/4" wrench, tighten it a little, then back off and tighten it again (repeating the process 'till it lines up to TDC.) However, I encountered a problem recently with a new Colt Upper Receiver assy. The F/H was a tad overtimed. Not enough to affect anything; I'm just anal about shit like that, and it pissed me off looking at it on there slightly cockeyed. So I put it in my vise on a Geisselle Reaction Rod. When putting it back on it went down hand-tight at almost 360 degrees off of TDC with a new crush washer. Tried another one with the same result. I was afraid I'd crush the threads on the barrel if I took it all the way around that far, so I used the old one which landed at about 350 degrees when hand tight. I just took it on to 360/TDC and left it. I just got back from my first range trip with the rifle, and the F/H didn't move. I don't use a torque wrench when putting on a F/H. Just tighten, loosen, tighten and repeat 'till it's aligned. Normally I don't reuse a crush washer either, but in this instance, I did.

All of my A2's and any other timed device are just past TDC,.....to as much as 1 o'clock. I'm right handed,.....that's where I want them. They force the muzzle down and slightly left where the recoil wants to take the muzzle up and to the right. Ever notice how an AK slant brake indexes?

I just put A2s or brakes on three muzzles last week and checked a dozen devices with about a dozen crush washers and damn near every combination hand tightened to around 1 o'clock requiring 360 degrees of rotation. I managed to mix and match until I found a few combinations that hand tightened closer to 3 o'clock and did the deed with those.

All of my A2's and any other timed device are just past TDC,.....to as much as 1 o'clock. I'm right handed,.....that's where I want them. They force the muzzle down and slightly left where the recoil wants to take the muzzle up and to the right. Ever notice how an AK slant brake indexes?

I just put A2s or brakes on three muzzles last week and checked a dozen devices with about a dozen crush washers and damn near every combination hand tightened to around 1 o'clock requiring 360 degrees of rotation. I managed to mix and match until I found a few combinations that hand tightened closer to 3 o'clock and did the deed with those.

^^^^^ +1 ^^^^^

This is proper way for a right handed shooter with muzzle brake unless instructions say different. I use PRI Quiet Control Brakes when use a brake instead of suppressor adapter. These are their mounting instructions to keep anyone from misinstalling their brakes.

Quote:

The brake comes with a selection of spacer shims to set the timing of the brake. The 3 holes should be at the 1 O'clock position when tightened into place. Tighten the brake into place using a round screw driver in the 1st slot closest to the barrel.*

My rifle smith of years always built custom compensators and would often try as many as three brakes to get best harmonics for barrel and would have ports at 1:00 o'clock slightly modified to help control direction rifle traveled as well. He had dozens of designs and lengths as a 300 Win Mag needed a linger brake with more ports than a 308 and a 7mm Practical or 7mm Mag needed longer device with more ports than a 7mm-08. Yes, properly clocking a muzzle brake is important but on a birdcage flash arrestor do not think it's a big deal.

Flash suppressor and muzzle brake are supposed to be separate things unless it's a design that does some of both and works around the laws of states that don't allow flash suppressors. If shoot prone much it is important to have it clocked to prevent dust signature in dry areas even with a three prong. If able to easily get bottom prong oriented at 6:00 o'clock I will usually put a little extra effort to do so though my ability to leap to the ground pop off a few shots then hop up and sprint to next spot is directly proportionate to how significant the threat is which doubt I will be in that type of battle conditions.

Nighttime flash is my biggest concern and use suppressors as much as can to knock down flash and sound signature. As to the PRI brake, purchased one used here, discovered like most brakes I really don't need a brake on 5.56 but put on my first 22 Nosler build on a whim and not only was it easier to control but apparently calmed down harmonics as group size shrank. Have used them on three different barrel makes in 22 Nosler and all shot slightly better with the PRI than a standard flash hider or other design brakes had in the box.

__________________
A time will come when people will not listen to accurate teachings. Instead, they will follow their own desires and surround themselves with teachers who tell them what they want to hear. 2 Timothy 4:3 G.W.T.
"If it is worth doing once...it's worth doing it a few more times to get it right." Stimpsonjcat

All of my A2's and any other timed device are just past TDC,.....to as much as 1 o'clock. I'm right handed,.....that's where I want them. They force the muzzle down and slightly left where the recoil wants to take the muzzle up and to the right. Ever notice how an AK slant brake indexes?

I just put A2s or brakes on three muzzles last week and checked a dozen devices with about a dozen crush washers and damn near every combination hand tightened to around 1 o'clock requiring 360 degrees of rotation. I managed to mix and match until I found a few combinations that hand tightened closer to 3 o'clock and did the deed with those.

I thought about that before I took the F/H off. I am familiar with the slanted brake on an AK. Just that most of the A2s I have bothered looking at over the years were right at TDC, and this one just pissed me off! Probably doesn't matter much either way! Never have bothered to do it, but I am sure you can remove a little material from a crush washer, and have it hand tighten to about wherever you desire it.

I use crush washers on flash hiders and shims on muzzle brakes. I especially like crush washers when use tack welds to pin a device. Can just snug device against crush washer and then start my arc on the crush washer and let puddle flow out till it just touches the shoulder of barrel and edge of device leaving 70% to 80% of weld puddle on washer and just barely grabbing the two parts supposed to join. Have my legally pinned device and then when need to part them later just put cut off wheel on crush washer, cut through weld into washer till can wrench it off. A quick touch with grinder and 99% of folks can't tell either were ever welded on and saves putting a pin through the threads of my muzzles. A fat crush washer is enough thicker than a standard cut off wheel that it never touches either the barrel or device when push through the weld.

__________________
A time will come when people will not listen to accurate teachings. Instead, they will follow their own desires and surround themselves with teachers who tell them what they want to hear. 2 Timothy 4:3 G.W.T.
"If it is worth doing once...it's worth doing it a few more times to get it right." Stimpsonjcat

All this talk of crush washers and shims makes me really appreciate my Patriot Valley Arms brakes. I set 'em on snug and forget about them. Due to the left hand thread on the nut that butts against the barrel shoulder, there's no chance of them coming unthreaded. Any torque imposed by the right-handed rifling will tighten the fit.